Scientists believe that haplogroup I originated with the Gravettian culture of Paleolithic Europe. One subclade,
known as I1, is common among Icelandic populations, and is generally considered to indicate Scandinavian or
Anglo-Saxon ancestry when it is found in a person of British descent.
I1 is currently believed to have originated during the Paleolithic, and to have taken refuge from the
Ice Age in Iberia. Afterwards, it spread northeast into other portions of Europe, such as The Low Countries,
Germany and Scandinavia.
(For more information about Haplogroup I and its various subclades, read this excellent study.)